• 대한원격탐사학회지
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• 제33권5_1호
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• pp.507-519
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• 2017

정규식생지수(NDVI, Normalized Difference Vegetation Index)는 생물량 및 $CO_2$ 흡수량 추정과 병충해 탐지 등 다양한 식생 모니터링 영역에서 활용되고 있다. 그러나, 생물량 탐지에 비해 상대적으로 식생의 생리적 상태 변화에 대한 민감도가 낮아 식생의 생리적 활성 및 스트레스를 파악에 한계가 있다. 최근 개발된 광학반사지수(PRI, Photochemical Reflectance Index)는 식생의 생리적 상태 탐지에 용이한 것으로 알려지고 있으며, 식생의 탄소 흡수량 조사를 위해 향후 발사될 해외의 지구관측위성들의 주요 산출물로 선정되는 등 활용도가 높아질 것으로 전망된다. 이에 다양한 이용에 앞서 광 스트레스에 민감한 PRI 특성을 고려하여 그림자 영향의 해석 방향을 제시하고, 현재 가용한 위성으로 PRI 산출이 가능한지 알아보기 위해 대체 밴드를 평가하였다. 항공 초분광 영상을 이용한 본 연구에서는 PRI값이 그림자 부분에서 광 스트레스의 감소로 인해 증가하였다. 그러나 그림자의 정도가 임계값(Shadow Index<25)을 넘어서면 PRI와 NDVI 모두의 자료 품질이 매우 낮아졌다. 또한, 문헌의 570.0 nm 대신 553.6 nm를 사용하여 산출한 PRI가 오리지널 PRI와 높은 상관관계를 보였으며, RED와 NIR 반사도를 이용하여 다중회귀분석을 수행하였을 때 더욱 향상된 결과를 보였다. 이러한 결과는 향후 식생탐지에서 활용도가 높아질 것으로 기대되는 PRI의 생리적인 의미를 이해하는데 도움이 될 것이다.

• 한국언어정보학회:학술대회논문집
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• 한국언어정보학회 2005년도 하계 학술대회
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• pp.151-165
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• 2005

• 대한방사선기술학회지:방사선기술과학
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• 제40권2호
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• pp.197-203
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• 2017

본 연구는 흉부영상에서 심장저부 음영 관심영역(Region of Interest; ROI)의 신호대잡음비(Signal to Noise Ratio; SNR)를 Post processing에서의 이퀄라이제이션 기법으로 측정 평가하였다. 연구대상은 대학병원에서 흉부검사를 실시한 환자 87명이다. 측정방법은 ImageJ 프로그램을 사용하여 표본의 인구사회학적 특성, 영상별 흉부영상의 SNR평균값, 95% 신뢰구간 값, SNR평균차이 값 등을 분석하였다. 이때 SPSS Statistics21 통계프로그램으로 ANOVA 분석을 하였으며, 95%(p < 0.05)에서 유의한 것으로 판단하였다. 영상별 분석결과의 SNR은 Original chest image, Original chest image heart shadow, Equalization chest image, Equalization chest image heart shadow순으로 높은 값을 나타냈다(p < 0.001). 결론적으로, 본 연구에서는 흉부영상의 평활화 시 심장저부 음영의 정량화한 평가결과를 보조적인 수단으로 활용할 수 있을 것으로 사료된다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.657-662
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• 2014

Background: The epidermal growth factor receptor (EGFR) mutation status of lung cancer is important because it means that EGFR-tyrosine kinase inhibitor treatment is indicated. The purpose of this prospective study is to determine whether EGFR mutation status could be identified with reference to preoperative factors. Materials and Methods: One hundred-forty eight patients with lung cancer (111 adenocarcinomas, 25 squamous cell carcinomas and 12 other cell types) were enrolled in this study. The EGFR mutation status of each lung cancer was analyzed postoperatively. Results: There were 58 patients with mutant EGFR lung cancers (mutant LC) and 90 patients with wild-type EGFR lung cancers (wild-type LC). There were significant differences in gender, smoking status, maximum tumor diameter in chest CT, type of tumor shadow, clinical stage between mutant LC and wild-type LC. EGFR mutations were detected only in adenocarcinomas. Maximum standardized uptake value (SUVmax:$3.66{\pm}4.53$) in positron emission tomography-computed tomography of mutant LC was significantly lower than that ($8.26{\pm}6.11$) of wild-type LC (p<0.0001). Concerning type of tumor shadow, the percentage of mutant LC was 85.7% (6/7) in lung cancers with pure ground glass opacity (GGO), 65.3%(32/49) in lung cancers with mixed GGO and 21.7%(20/92) in lung cancers with solid shadow (p<0.0001). For the results of discriminant analysis, type of tumor shadow (p=0.00036) was most significantly associated with mutant EGFR. Tumor histology (p=0.0028), smoking status (p=0.0051) and maximum diameter of tumor shadow in chest CT (p=0.047) were also significantly associated with mutant EGFR. The accuracy for evaluating EGFR mutation status by discriminant analysis was 77.0% (114/148). Conclusions: Mutant EGFR is significantly associated with lung cancer with pure or mixed GGO, adenocarcinoma, never-smoker, smaller tumor diameter in chest CT. Preoperatively, EGFR mutation status can be identified correctly in about 77 % of lung cancers.

• 한국측량학회지
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• 제27권3호
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• pp.357-365
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• 2009

건설현장의 인력 및 장비의 위치 추적을 위한 RTLS(Real-Time location system)이 개발 중이며, 이중에는 무선랜 기반의 전파방식을 활용하는 기법도 고려되고 있다. 이 기법을 건설현장에 도입하기 위해서는 RTLS의 AP(Access Point) 전파가 도달하는 거리를 고려한 3차원 가시선 분석을 통해 사전에 AP의 설치 위치를 모의해야 할 필요가 있다. 본 연구에서는 지상라이다로 획득된 공간자료를 격자화하고, AP 설치 위치의 모의를 위한 3차원 가시선 분석의 성능 향상을 위하여 여러 가지 격자크기에 대해 두 가지 가시종단선 처리기법을 적용하고, 그 결과를 비교하였다. 가시면적에 대한 평가결과 선긋기기법이 그림자기법 보다 약 7.4%의 많은 가시영역을 나타내었으나, 그림자기법이 격자크기에 대해 안정적인 결과를 나타내었고, 처리시간에 대해서는 선긋기기법이 그림자기법에 비해 2배 가까이 빠른 것으로 나타났다.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.368-375
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• 2010

Unlike document images, license plate images are mostly captured under uneven lighting conditions. In particular, a shadowed region has sharp intensity variation and sometimes that region has very high intensity by reflected light. This paper presents a new technique for thresholding license plate images. This approach consists of three parts. In the first part, it performs a rough thresholding and classifies the type of license plate to adjust some parameters optimally. Next, it identifies a shadow type and binarizes license plate images by adjusting the window size and location according to the shadow type. And finally, post-processing based on the cluster analysis is performed. Experimental results show that the proposed method outperformed five well-known methods.

• Wind and Structures
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• 제17권6호
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• pp.589-608
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• 2013

A model is proposed to analyse the along-wind dynamic response of upwind turbines with horizontal axis under service wind conditions. The model takes into account the dynamic coupling effect between rotor blades and supporting tower. The wind speed field is decomposed into a mean component, accounting for the well-known wind shear effect, and a fluctuating component, treated through a spectral approach. Accordingly, the so-called rotationally sampled spectra are introduced for the blades to account for the effect of their rotating motion. Wind forces acting on the rotor blades are calculated according to the blade element momentum model. The tower shadow effect is also included in the present model. Two examples of a large and medium size wind turbines are modelled, and their dynamic response is analysed and compared with the results of a conventional static analysis.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2004년도 학술발표논문집
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• pp.42-42
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• 2004

• 천문학회지
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• 제51권4호
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• pp.119-127
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• 2018

We examine whether the solar eclipse effect is dependent on the geographic conditions under which the geomagnetic field variations are recorded. We concentrate our attention on the dependence of the solar eclipse effect on a number of factors, including, the magnitude of a solar eclipse (defined as the fraction of the angular diameter of the Sun being eclipsed), the magnetic latitude of the observatory, the duration of the observed solar eclipse at the given geomagnetic observatory, and the location of the geomagnetic observatory in the path of the Moon's shadow. We analyze an average of the 207 geomagnetic field variation data sets observed by 100 INTERMAGNET geomagnetic nodes, during the period from 1991 to 2016. As a result, it is demonstrated that (1) the solar eclipse effect on the geomagnetic field, i.e., an increase in the Y component and decreases in the X, Z and F componenets, becomes more distinct as the magnitude of solar eclipse increases, (2) the solar eclipse effect is most conspicuous when the modulus of the magnetic latitude is between $30^{\circ}$ and $50^{\circ}$, (3) the more slowly Moon's shadow passes the geomagnetic observatory, the more clear the solar eclipse effect, (4) the geomagnetic observatory located in the latter half of the path of Moon's shadow with respect to the position of the greatest eclipse is likely to observe a more clear signal. Finally, we conclude by stressing the importance of our findings.

• 한국초등과학교육학회지:초등과학교육
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• 제37권3호
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• pp.285-295
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• 2018

The purpose of this study is comparing cognitive development of elementary $4^{th}$ graders and cognitive demand of activities in lesson 'The mirror and the shadow.' Also, the researchers tried to reveal how cognitive development of elementary $4^{th}$ graders and cognitive demand of textbook activities affects the achievement of students. To study students' cognitive development, the researchers use GALT(Group Assessment of Logical Thinking). Piaget's scientific thinking is used to evaluate cognitive demand of textbook activities. With several experts in science education the researchers discussed which scientific thinking is contained in each activities. The results were followed as : (1) The third of activities are significantly affected by students' cognitive development. (2) The another third of activities are influenced by not only students' cognitive development but also other factors experimental instrument. (3) The environmental factors had meaningful impact on the other third of activities.